PERMANENT DEFORMATION BEHAVIOR OF THE GRANULAR LAYERS TESTED AT THE FAA’s NATIONAL AIRPORT PAVEMENT TEST FACILITY NAVNEET GARG, Ph.D. Senior Research Engineer, Galaxy Scientific Corp., EHT, NJ 82 nd Annual Meeting of the Transportation Research Board Modeling of Granular Bases for Flexible Pavements Session-556 January 14, 2003, Washington DC

PRESENTATION OUTLINE  National Airport Pavement Test Facility  Unbound Granular Materials  Measurements  Traffic Tests  Results  Summary

NAPTF PAVEMENT CROSS-SECTIONS 5-inch P-401 Surface 5-inch P-401 Base 8.5-inch P-209 Subbase MFS Medium- Strength Subgrade 5-inch P-401 Surface 5-inch P-401 Base High-Strength Subgrade HFS 5-inch P-401 Surface 5-inch P-401 Base 30-inch P-209 Subbase Low-Strength Subgrade LFS 5-inch P-401 Surface 8-inch P-209 Base 36-inch P-154 Subbase LFC Medium-Strength Subgrade 5-inch P-401 Surface 8-inch P-209 Base 12-inch P-154 Subbase MFC High-Strength Subgrade 5-inch P-401 Surface 11-inch P-209 Base HFC Low-Strength Subgrade 11-inch P-501 Surface 6-inch P-306 Base 8-inch P-154 Subbase LRS Medium-Strength Subgrade 10-inch P-501 Surface 6-inch P-306 Base 8-inch P-154 Subbase MRS High-Strength Subgrade 9-inch P-501 Surface 6-inch P-306 Base 6-inch P-154 Subbase HRS

PRESENTATION OUTLINE

Maximum Dry Density: pcf Optimum Moisture Content: 7.10 % P-209 CRUSHED STONE BASE

Maximum Dry Density: pcf Optimum Moisture Content: 6.5 % P-154 SUBBASE

SHRP P-46 RESILIENT MODULUS TEST RESULTS

PRESENTATION OUTLINE

Low-Strength Subgrade End High-Strength Subgrade End 6-Wheel Traffic Path 4-Wheel Traffic Path Pavement Center Line NE-MDD SE-MDD NW-MDD CL-MDD SW-MDD

LEFT OFFSET RIGHT OFFSET PEAK-1PEAK-2 PEAK-3 TOTAL DEFORMATION RECOVERED DEFORMATION UNRECOVERED DEFORMATION MDD RESPONSE-TIME HISTORY

RUT DEPTH MEASUREMENTS

PRESENTATION OUTLINE

TRAFFIC TESTS  Vehicle Speed: 5-mph (8-kmph)  Failure Criteria: 1-inch (25-mm) upheaval outside the traffic path  Wheel Load: -45,000-lbs (20.4 metric tonnes) per wheel -After 20,000 45,000-lbs, LFS & LFC further 65,000-lbs (29.5 metric tonnes)

PRESENTATION OUTLINE

LFS – LAYER PROFILES

LFC – LAYER PROFILES

MFC-W – LAYER PROFILES

RUT DEPTH MEASUREMENTS

MFS-W – LAYER PROFILES

MFS-E – LAYER PROFILES

PRESENTATION OUTLINE

SUMMARY  Of the 6 flexible pavement sections tested- LFS & LFC –Rutting/shoving in P-401 layer, rutting in P-209 & P-154 layer. rutting in P-209 & P-154 layer. MFS & MFC –Rutting in subgrade, P-209 & P-154 layer. HFS & HFC – No signs of failure, traffic tests suspended.

SUMMARY  The total accumulated permanent deformation in the pavement structure over a complete wander pattern (66 passes) is a small fraction of the total range of the unrecovered deformation occurring during the wander cycle.  Recovered and unrecovered displacements due to traffic loading increased significantly as the pavement was trafficked to failure.